Potential applications of near-infrared imaging in eye care beyond the established use cases: A scoping review

SIGNIFICANCE: Near-infrared (NIR) imaging, through novel technology or through adaptation of existing technology, is a useful tool for detecting and screening ocular abnormalities. PURPOSE: This scoping review determined (1) the novel use cases of NIR imaging for the in vivo identification of ocular abnormalities and (2) if these technologies involved purpose-built designs or an adaptation of existing technology for achieving its intended usage. METHODS: Query strings were created using an initial limited search in PubMed and Scopus data sources. Articles subsequently identified on a secondary search using Scopus, PubMed, and ScienceDirect data sources were filtered based on their title and abstract (primary screening) and on their methods and results (secondary screening). The final search was from the citations of the finalized articles. Articles that detailed the technology used, its intended use cases, and the value addition to the eye care ecosystem were included. Technologies well-integrated into clinical practice were excluded. RESULTS: Of the 1431 articles identified, 22 were selected for full-text reading. The selected articles, published between 1978 and 2022, used NIR light for three applications: (1) as a transillumination source for detecting anterior segment abnormalities (n = 17); (2) as a photorefractor for identifying corneal ectasias like keratoconus (n = 3), and (3) as an illumination source for detecting media opacities using devices unintended for ophthalmic use (n = 3). The first application employed a video slit-lamp biomicroscope or a purpose-built imaging apparatus while placing the NIR transilluminator on the cornea, palpebra, or sclera. The remaining applications illuminated the eye noninvasively and analyzed the resultant pupillary reflex using standard image processing. All studies demonstrated high accuracy of NIR light in detecting ocular abnormalities compared with visible light. However, they were all proofs-of-concept, with relatively homogenous disease profiles and limited sample size for assessing diagnostic accuracy. CONCLUSIONS: NIR imaging holds promise for improved detection and screening of several anterior segment ocular abnormalities, relative to visible light. The clinical adoption rates of many of these technologies have been low. This may arise from several factors, including paucity of strong evidence of their utility from clinical trials and/or lack of commercialization due to limited perceived market for such technologies.